There is an urgent need to improve our diagnostic capabilities and treatment of glioma tumors. This project combines novel genetic and imaging methods that specifically address these needs. In Aim 1 we will explore whether endogenous neuroprecursor cells in adult animals will migrate to tumors in the brain and whether they can be genetically modified to deliver new therapeutic proteins, including secreted forms of the apoptosis-inducing protein, S-TRAIL, to kill tumor cells, as well as a decoy receptor for the vascular endothelial cell growth factor (VEGF) receptor to block angiogenesis. Aim 2 will focus on development of biomolecular sensors to report from the tumor environment. The first sensor will be a metabolically biotinylated cell surface marker synthesized by cells under promoters that respond to angiogenic or hypoxic signals in the tumor. The second sensor will be a caged form of Gaussia luciferase quenched by flanking protein sequences, which can be selectively cleaved by metalloproteinases in the extracellular tumor matrix, thus restoring luciferase activity. Aim 3 will identify peptides displayed on the AAV capsid, which can mediate passage of particles across the blood-tumor barrier. This will involve in vivo selection of a novel AAV peptide-display library designed to isolate infected cells of specific phenotypes from the tumors. Targeting vectors will be tested for improved delivery of biomolecular sensors and therapeutic proteins, and peptides will be evaluated for delivery of other macromolecules to tumors. These studies combine "designer" recombinant proteins, genetically modified cells, and virus vectors with state-of-the-art methods of bioluminescence, fluorescence and MR imaging to monitor delivery and responses using human tumor cells implanted in the periphery and brains of nude mice. We hypothesize that these approaches will allow more efficient diagnosis and objective treatment evaluation of central nervous tumors, with broad applicability to other types of tumors. This work will be carried out in collaboration with Project 4 (fluorescent protein tomography) and Pilot Project 1 (neuroprecursor cell line), and will depend on the Mouse Imaging Core and Chemistry Core.